Pneumatic tire

Abstract

In a pneumatic tire, a first shoulder block comprises at least one first shoulder circumferential groove which extends in a tire circumferential direction, the at least one first shoulder circumferential groove is respectively separated from a pair of first shoulder slits, a center block comprises at least one center circumferential groove which extends in the tire circumferential direction, and the at least one center circumferential groove is respectively contiguous with a pair of center slits.

The invention claimed is: 
     
       1. A pneumatic tire comprising a plurality of main grooves extending in a tire circumferential direction, and a plurality of lands which are partitioned by the plurality of main grooves and a pair of contact patch ends, wherein:
 the plurality of lands comprise
 first and second shoulder lands which are arranged so as to be outwardmost in a tire axial direction, 
 a center land which is arranged nearest to a tire equatorial plane, and 
 a second mediate land which is arranged between the second shoulder land and the center land; 
 
 the first shoulder land comprises a plurality of first shoulder slits which each extend across a full width of the first shoulder land in the tire axial direction, and a first shoulder block which is partitioned by a pair of first shoulder slits which among the plurality of first shoulder slits are mutually adjacent in the tire circumferential direction; 
 the first shoulder block comprises at least one first shoulder circumferential groove which extends in the tire circumferential direction; 
 the at least one first shoulder circumferential groove is respectively separated from the pair of first shoulder slits; 
 the center land comprises a plurality of center slits which each extend across a full width of the center land in the tire axial direction, and a center block which is partitioned by a pair of center slits which among the plurality of center slits are mutually adjacent in the tire circumferential direction; 
 the center block comprises at least one center circumferential groove which extends in the tire circumferential direction; 
 the at least one center circumferential groove is respectively contiguous with the pair of center slits; 
 the second mediate land comprises a plurality of second mediate slits which each extend across a full width of the second mediate land in the tire axial direction, 
 the plurality of second mediate slits comprise
 a first adjacent slit, 
 a second adjacent slit which is adjacent to the first adjacent slit at a first side in the tire circumferential direction, and 
 a third adjacent slit which is adjacent to the first adjacent slit at a second side in the tire circumferential direction; 
 
 the second mediate land further comprises
 a second mediate block which is partitioned by the first adjacent slit and the second adjacent slit, and 
 a third mediate block which is partitioned by the first adjacent slit and the third adjacent slit; 
 
 the second mediate block comprises at least one second mediate circumferential groove which extends in the tire circumferential direction; 
 all of the at least one second mediate circumferential groove is contiguous with the first adjacent slit but is separated from the second adjacent slit; 
 the third mediate block comprises at least one third mediate circumferential groove which extends in the tire circumferential direction; and 
 all of the at least one third mediate circumferential groove is contiguous with the first adjacent slit but is separated from the third adjacent slit. 
 
     
     
       2. The pneumatic tire according to  claim 1  wherein
 the plurality of lands further comprise a first mediate land which is arranged between the first shoulder land and the center land; 
 the first mediate land comprises a plurality of first mediate slits which each extend across a full width of the first mediate land in the tire axial direction, and a first mediate block which is partitioned by a pair of first mediate slits which among the plurality of first mediate slits are mutually adjacent in the tire circumferential direction; 
 the first mediate block comprises at least one first mediate circumferential groove which extends in the tire circumferential direction; and 
 the at least one first mediate circumferential groove is respectively separated from the pair of first mediate slits. 
 
     
     
       3. The pneumatic tire according to  claim 2  wherein the at least one first mediate circumferential groove is arranged toward an interior in the tire axial direction from a center in the tire axial direction of the first mediate block. 
     
     
       4. The pneumatic tire according to  claim 2  wherein
 the first mediate block comprises at least one first mediate sipe which extends in the tire axial direction; and 
 a groove width of the first mediate circumferential groove is greater than a groove width of the at least one first mediate sipe. 
 
     
     
       5. The pneumatic tire according to  claim 4  wherein
 the at least one first mediate sipe is part of a plurality of first mediate sipes; and 
 the first mediate circumferential groove intersects all of the first mediate sipes. 
 
     
     
       6. The pneumatic tire according to  claim 5  wherein
 the at least one first mediate sipe comprises at least one straight portion which extends in straight fashion, and at least one zigzag portion which extends in zigzag fashion; and 
 the first mediate circumferential groove intersects the at least one straight portion of the at least one first mediate sipe. 
 
     
     
       7. The pneumatic tire according to  claim 1  wherein the at least one second mediate circumferential groove extends so as to be inclined with respect to the tire circumferential direction. 
     
     
       8. The pneumatic tire according to  claim 1  wherein
 the first shoulder block comprises at least one first shoulder sipe which extends in the tire axial direction; and 
 a groove width of the first shoulder circumferential groove is greater than a groove width of the at least one first shoulder sipe. 
 
     
     
       9. The pneumatic tire according to  claim 8  wherein
 the at least one first shoulder sipe is part of a plurality of first shoulder sipes; and 
 the first shoulder circumferential groove intersects all of the first shoulder sipes. 
 
     
     
       10. The pneumatic tire according to  claim 9  wherein
 the at least one first shoulder sipe comprises at least one straight portion which extends in straight fashion, and at least one zigzag portion which extends in zigzag fashion; and 
 the first shoulder circumferential groove intersects the at least one straight portion of the at least one first shoulder sipe. 
 
     
     
       11. The pneumatic tire according to  claim 1  wherein
 the center block comprises at least one center sipe which extends in the tire axial direction; and 
 a groove width of the center circumferential groove is greater than a groove width of the at least one center sipe. 
 
     
     
       12. The pneumatic tire according to  claim 11  wherein
 the at least one center sipe is part of a plurality of center sipes; and 
 the center circumferential groove intersects all of the center sipes. 
 
     
     
       13. The pneumatic tire according to  claim 12  wherein
 the at least one center sipe comprises at least one straight portion which extends in straight fashion, and at least one zigzag portion which extends in zigzag fashion; and 
 the center circumferential groove intersects the at least one zigzag portion of the at least one center sipe. 
 
     
     
       14. The pneumatic tire according to  claim 1  wherein
 the second mediate block comprises at least one second mediate sipe which extends in the tire axial direction; and 
 a groove width of the second mediate circumferential groove is greater than a groove width of the at least one second mediate sipe. 
 
     
     
       15. The pneumatic tire according to  claim 14  wherein
 the at least one second mediate sipe is part of a plurality of second mediate sipes; and 
 the second mediate circumferential groove intersects all of the second mediate sipes. 
 
     
     
       16. The pneumatic tire according to  claim 15  wherein
 the at least one second mediate sipe comprises at least one straight portion which extends in straight fashion, and at least one zigzag portion which extends in zigzag fashion; and 
 the second mediate circumferential groove intersects the at least one zigzag portion of the at least one second mediate sipe. 
 
     
     
       17. The pneumatic tire according to  claim 1  wherein
 the second shoulder land comprises a plurality of second shoulder slits which each extend across a full width of the second shoulder land in the tire axial direction, and a second shoulder block which is partitioned by a pair of second shoulder slits which among the plurality of second shoulder slits are mutually adjacent in the tire circumferential direction; 
 the second shoulder block comprises at least one second shoulder circumferential groove which extends in the tire circumferential direction; and 
 the at least one second shoulder circumferential groove is respectively separated from the pair of second shoulder slits. 
 
     
     
       18. The pneumatic tire according to  claim 17  wherein
 the second shoulder block comprises at least one second shoulder sipe which extends in the tire axial direction; 
 a groove width of the second shoulder circumferential groove is greater than a groove width of the at least one second shoulder sipe; 
 the at least one second shoulder sipe is part of a plurality of second shoulder sipes; and 
 the second shoulder circumferential groove intersects all of the second shoulder sipes; 
 the at least one second shoulder sipe comprises at least one straight portion which extends in straight fashion, and at least one zigzag portion which extends in zigzag fashion; and 
 the second shoulder circumferential groove intersects the at least one zigzag portion of the at least one second shoulder sipe. 
 
     
     
       19. A pneumatic tire comprising a plurality of main grooves extending in a tire circumferential direction, and a plurality of lands which are partitioned by the plurality of main grooves and a pair of contact patch ends, wherein:
 the plurality of lands comprise
 first and second shoulder lands which are arranged so as to be outwardmost in a tire axial direction, 
 a center land which is arranged nearest to a tire equatorial plane, and 
 a second mediate land which is arranged between the second shoulder land and the center land; 
 
 the first shoulder land comprises a plurality of first shoulder slits which each extend across a full width of the first shoulder land in the tire axial direction, and a first shoulder block which is partitioned by a pair of first shoulder slits which among the plurality of first shoulder slits are mutually adjacent in the tire circumferential direction; 
 the first shoulder block comprises at least one first shoulder circumferential groove which extends in the tire circumferential direction; 
 the at least one first shoulder circumferential groove is respectively separated from the pair of first shoulder slits; 
 the center land comprises a plurality of center slits which each extend across a full width of the center land in the tire axial direction, and a center block which is partitioned by a pair of center slits which among the plurality of center slits are mutually adjacent in the tire circumferential direction; 
 the center block comprises at least one center circumferential groove which extends in the tire circumferential direction; 
 the at least one center circumferential groove is respectively contiguous with the pair of center slits; 
 the second mediate land comprises a plurality of second mediate slits which each extend across a full width of the second mediate land in the tire axial direction, 
 the plurality of second mediate slits comprise
 a first adjacent slit, 
 a second adjacent slit which is adjacent to the first adjacent slit at a first side in the tire circumferential direction, and 
 a third adjacent slit which is adjacent to the first adjacent slit at a second side in the tire circumferential direction; 
 
 the second mediate land further comprises
 a second mediate block which is partitioned by the first adjacent slit and the second adjacent slit, and 
 a third mediate block which is partitioned by the first adjacent slit and the third adjacent slit; 
 
 the second mediate block comprises at least one second mediate circumferential groove which extends in the tire circumferential direction; 
 all of the at least one second mediate circumferential groove is contiguous with the first adjacent slit but is separated from the second adjacent slit; 
 the third mediate block comprises at least one third mediate circumferential groove which extends in the tire circumferential direction; 
 all of the at least one third mediate circumferential groove is contiguous with the first adjacent slit but is separated from the third adjacent slit; 
 a depth of the first adjacent slit is less than a depth of the second adjacent slit; and 
 the depth of the first adjacent slit is less than a depth of the third adjacent slit. 
 
     
     
       20. A pneumatic tire comprising a plurality of main grooves extending in a tire circumferential direction, and a plurality of lands which are partitioned by the plurality of main grooves and a pair of contact patch ends, wherein:
 the plurality of lands comprise
 first and second shoulder lands which are arranged so as to be outwardmost in a tire axial direction, 
 a center land which is arranged nearest to a tire equatorial plane, and 
 a second mediate land which is arranged between the second shoulder land and the center land; 
 
 the first shoulder land comprises a plurality of first shoulder slits which each extend across a full width of the first shoulder land in the tire axial direction, and a first shoulder block which is partitioned by a pair of first shoulder slits which among the plurality of first shoulder slits are mutually adjacent in the tire circumferential direction; 
 the first shoulder block comprises at least one first shoulder circumferential groove which extends in the tire circumferential direction; 
 the at least one first shoulder circumferential groove is respectively separated from the pair of first shoulder slits; 
 the center land comprises a plurality of center slits which each extend across a full width of the center land in the tire axial direction, and a center block which is partitioned by a pair of center slits which among the plurality of center slits are mutually adjacent in the tire circumferential direction; 
 the center block comprises at least one center circumferential groove which extends in the tire circumferential direction; 
 the at least one center circumferential groove is respectively contiguous with the pair of center slits; 
 the second mediate land comprises a plurality of second mediate slits which each extend across a full width of the second mediate land in the tire axial direction, 
 the plurality of second mediate slits comprise
 a first adjacent slit, 
 a second adjacent slit which is adjacent to the first adjacent slit at a first side in the tire circumferential direction, and 
 a third adjacent slit which is adjacent to the first adjacent slit at a second side in the tire circumferential direction; 
 
 the second mediate land further comprises
 a second mediate block which is partitioned by the first adjacent slit and the second adjacent slit, and 
 a third mediate block which is partitioned by the first adjacent slit and the third adjacent slit; 
 
 the second mediate block comprises at least one second mediate circumferential groove which extends in the tire circumferential direction; 
 all of the at least one second mediate circumferential groove is contiguous with the first adjacent slit but is separated from the second adjacent slit; 
 the third mediate block comprises at least one third mediate circumferential groove which extends in the tire circumferential direction; 
 all of the at least one third mediate circumferential groove is contiguous with the first adjacent slit but is separated from the third adjacent slit; 
 the all of the at least one second mediate circumferential groove is arranged toward an interior in the tire axial direction from a center in the tire axial direction of the second mediate block; and 
 the all of the at least one third mediate circumferential groove intersects a center in the tire axial direction of the third mediate block.